UL588 cls 49这个测试怎么做？什么意思呀？

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UL588 cls 49这个测试怎么做？什么意思呀？
49 Component Power Measurement Test
49.1 To determine if a component or a circuit of a seasonal lighting product is capable of delivering 15
watts of power for one minute (see 48.1, Exception No. 1(c)), the component shall be tested as described
in 49.2 – 49.4.
49.2 The unit is to be connected to a 60 Hz, 120 V supply source. One component or circuit of the unit
is to be connected to a wattmeter and an adjustable external load resistor as illustrated in Figure 49.1.
The external load resistor is to be set for its maximum resistance. A closed shorting switch is to be
connected across the unit’s protective device, such as a fuse, and the resistor is then to be adjusted to
cause a power dissipation of exactly 15 watts as indicated by the meter. The shorting switch across the
protective device is then to be opened and the time required for the protective device to open is to be
recorded.
49.3 During the test, the supply circuit is to be protected by a 20 A time delay fuse, with characteristics
such that the fuse will not open in less than 12 seconds when carrying 40 A.
49.4 The point of measurement of the circuit (see Figure 49.1) is not considered capable of delivering 15
watts for one minute if:
a) The protective device of the unit opens in less than 60 seconds,
b) A circuit component opens in less than one minute, or
c) The current is inherently limited by the circuit.